Many investigations have reported that ancillary services in hospitals (e.g., laboratory tests, radiological examinations, electroencephalograms) are often unnecessarily ordered. This project will develop criteria to identify the appropriate and inappropriate ordering of five ancillary services for hospitalized patients. It will also test the utility of the criteria by evaluating the ordering of the five services in two hospitals, a teaching hospital, and a non-teaching hospital. During the first year the criteria will be developed for the five services: arterial blood gas, serum electrolytes, chest x-rays, electrocardiograms, and complete blood counts. The criteria will indicate the appropriate initial ordering and ongoing monitoring use of the services. The criteria development will require meetings of panels of experts and subsequent reviews of the criteria by nationally prominent reviewers. During the second year of the project the criteria will be converted to an evaluation instrument (i.e., abstracting form) to collect data from medical records. Data will be collected from at least 127 patients from each service at each hospital. The data will be analyzed to determine the extent of appropriate ordering, inappropriate ordering, and failure to order when appropriate. The development of the criteria and evaluation methodology are of great importance under the new fixed payment systems for hospital services being implemented at national and local levels. Physicians are under increasing pressure to reduce care costs by reducing the order to ancillary services. The criteria will provide direction for the reduction of inappropriate ordering while maintaining appropriate ordering. The evaluation methodology will provide a means of external verification of the delivery of appropriate and efficient care. The trial results will provide insight into common problems causing inappropriate ordering and recommendations for approaches to produce appropriate reductions in ordering. The overall project will indicate the success with which criteria for appropriate and inappropriate ordering of ancillary services can be developed and the resources required to develop criteria and to evaluate ordering practices.